As procedures for expanding a stenosis formed in living body blood vessels, so-called percutaneous transluminal angioplasty (PTA) or percutaneous transluminal coronary angioplasty (PTCA) which is performed by using a balloon catheter is widely known. In the procedures using the balloon catheter, an operation inserting a guidewire into a stenosis is carried out first. Subsequently, an operator's hand operates the balloon catheter so as to be guided by the guidewire, thereby pushing the overall balloon catheter and inserting a balloon into the stenosis. Thereafter, the stenosis (treating area) is spread out by inflating the balloon, thereby restoring a blood flow therein.
The balloon catheter includes the balloon to which a fluid serving as a pressurizing medium is injected, an inner tube into which the guidewire is inserted in order to guide the balloon catheter to the stenosis, and an outer tube which forms a lumen capable of injecting the fluid between the inner tube and the outer tube. The inner tube and the outer tube are configured to generally include a thin and flexible elongated member which is improved in order to follow living body organs or the like (for example, blood vessels) which are curved and thin. An example of a balloon catheter is disclosed in Japanese Application Publication No. 2002-291897.